Agitator



J. E. BOND Dec. 3, 1929.

AG I TATOR Filed March 5, 1928 Patented Dec. 3, 1929 \l J'bSEPH E. BOND, OF APPLETON, WISCONSIN AGITATOR Application filed larch 5,

My invention relates to the art of paper maklng and particularly to means for agitating paper pulp. r

In the development of the art it has been found possible to greatly increasethe capacity of a given equipment by increasing the density (or, in other words, lessenlng the fluidity) of the pulp during its treatment preceding delivery to the Fourdrimers. Wh1le 1n the old practice a 2 pulp was consldered proper and of the maximum denslty possible, it is now common to deal with 6% solutions, with correspondingly increased production capacity.

However, man diflicult problems are encountered in han ling pulp of this density due to its lack of fluidity and its tendency to mass or cake in the storage or treatment tanks and containers. This tendency is inherent in the nature of the material under treatment due to its fibrous character and to the physical law of attraction of solids. The liquid within which the solids are carried serves merely as a supporting medium therefor and facilitates rather than hinders the massing and intertwining of the fibers.

To avoid massing and stratifying of the pulp in the liquid and to maintain a uniform density throughout the entire body of material it must be kept in motion and the motion producing means should have a tendency to break up and tear apart-any large or small masses of pulp. In the old practice the mixture was kept in motion by means of paddles or impellers in the tank, but this apparatus had very little tendency to break up masses of pulp, and was wholly inefiective with stock of increased density. Furthermore, such apparatus required an outlay of power not commensurate with the results secured.

The tanks, chests or containers which are in place and must be utilized for the new plan of operation are of many and varied forms, all of great size, some narrow and of great length, some deep and some round. The problem has been, therefore, to provide means applicable to these various forms of tanks that would insure eflective circulation, the breaking up of pulp masses and the maintenance at all times of a proper consistency 1928. Serial No. 259,080.

throughout the whole volume of material, with a minimum of power expenditure.

My invention will be more readily understood by reference to the accompanying drawings, in which i Fig. 1 is a plan view of an agitator arranged in accordance with my invention, and

Fig; 2 is a transverse vertical sectional view on the line 2-2 of Fig. 1.

In the drawings I have illustrated a circular tank 10, mounted on a concrete floor or base 11 which is dished so that the lowest point is at the center of the tank. Mounted within the tank is a wall 12, one end 13 of which is connected to or abuts the exterior wall of the tank and the inner end 14 of which terminates at a point close to the center of the tank. The wall is of generally volute form thereby providing a long gradually converging or spiral passage beginning at a point near the periphery of the tank and terminating at its center. While the wall conforms to the circular outline of the tank throughout a portion of its length, this is done for convenience in bending and in stalling the sheet steel constituting the wall. The-desired effect, however, is that of the provision of a spiral or volute passage in order to direct the material from a point near the exterior wall to the center. In order to stifi'en and support the sheet metal wall, I connect stays 15, 16, 17 across the same at the top, as shown. A stock'inlet pipe 18 to a storage tank is illustrated in Fig. 2.

A pump 19 is provided having an inlet pipe 20 terminating in a valved inlet opening 21 at the center of the tank immediately above the lower point thereof. An outlet pipe 22 projects upwardly from the pump and terminates in the space at the beginning of the volute passage. A pipe 23 is connected to the pump inlet pipe 20 for the purpose of withdrawing pulp for use as required.

The pipe 22 may discharge into the bottom, as shown, or it may be extended vertically far enough to roll the stock and prevent the current from cutting under the floating material. Chemical stock has a tendency to float due to a surrounding film of chemicals and gas. Therefore, it is essential to change the plane and cause the stock to roll. One principle of operation of the agitator is to insure a velocity of flow that will pass all the stock through the agitator before it can either settle to the bottom or float.

The ump being in operation and a quantity of liquid contained within the tank it is withdrawn from the chamber at'the center through the pump and discharged upwardly with considerable velocity. It travels along the converging passage beingkept constantly in motion and finally reaches the central chamber from which it isagain withdrawn.

I claim:

1. In combination, a circular tank, a generally volute wall connected to the'tank wall at one end and terminating near the center of the tank at its other end, a pump having an inlet pipe communicating with the tank at the center near the floor thereof and an outlet pipe discharging into a space near the periphery of the tank adjacent to the junction of said volute Wall and said tank wall.

2. In combination, a circular tank, a vertical wall therein providing a passage that extends entirely around the tank and converges to a point near the center thereof, an impeller pump connected to draw material from' the center of the tank and to discharge said material near the wall of the tank into the space at the beginning of said passage.

3. In combination, a circular tank, a vertical wall therein providing a passage that extends at least twice around the tank and converges to a point near the center thereof, an impeller pump connected to draw material from the center of the tank and to discharge said material near the Wall of the tank into the space at the beginning of said passage.

In testimony whereof I have afiixed my signature.

JOSEPH E. BOND. 

